diff --git a/backend/services/controller/internal/db/db.go b/backend/services/controller/internal/db/db.go
index 257684d..8f3271f 100644
--- a/backend/services/controller/internal/db/db.go
+++ b/backend/services/controller/internal/db/db.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"log"
 
+	"go.mongodb.org/mongo-driver/bson"
 	"go.mongodb.org/mongo-driver/mongo"
 	"go.mongodb.org/mongo-driver/mongo/options"
 )
@@ -11,6 +12,7 @@ import (
 //TODO: create another package fo structs and interfaces
 
 type Database struct {
+	client  *mongo.Client
 	devices *mongo.Collection
 	users   *mongo.Collection
 	ctx     context.Context
@@ -18,11 +20,14 @@ type Database struct {
 
 func NewDatabase(ctx context.Context, mongoUri string) Database {
 	var db Database
+
 	clientOptions := options.Client().ApplyURI(mongoUri)
 	client, err := mongo.Connect(ctx, clientOptions)
 	if err != nil {
 		log.Fatal(err)
 	}
+	db.client = client
+
 	log.Println("Trying to ping Mongo database...")
 	err = client.Ping(ctx, nil)
 	if err != nil {
@@ -30,10 +35,24 @@ func NewDatabase(ctx context.Context, mongoUri string) Database {
 	}
 
 	log.Println("Connected to MongoDB-->", mongoUri)
+
 	devices := client.Database("oktopus").Collection("devices")
+	createIndexes(ctx, devices)
+
 	users := client.Database("oktopus").Collection("users")
 	db.devices = devices
 	db.users = users
 	db.ctx = ctx
 	return db
 }
+
+func createIndexes(ctx context.Context, devices *mongo.Collection) {
+	indexField := bson.M{"sn": 1}
+	_, err := devices.Indexes().CreateOne(ctx, mongo.IndexModel{
+		Keys:    indexField,
+		Options: options.Index().SetUnique(true),
+	})
+	if err != nil {
+		log.Println("ERROR to create index in database:", err)
+	}
+}